What exactly is "imaging" ?

[George J]

I have been following this thread and reading every post.

I have zero interest in left/right separation, My system [such as it is] is a 1957 Leak Trough-Line VHF/ FM tuner, Quad II Forty amp and ESL. It couldy be hardly be more direct with discrete components. No pre-amp as the tuner has a nice cathode follower [variable] output that perfectly matches any mono-block valve amp.

So I am not worried by the stereo recreations of say my hero, Ella Fitzgerald, and mono records still compete, though the recording side of my set does not fed the ESL. The best live VHF/FM is simply still better than almost any recording as produced and issued commercials.

So I am going to join the debate regarding vertical perception from systems designed for left/right separation or mono that does not.

If one knows a concert venue, then one knows where the reverberation comes from. I listen to The BBC Proms most nights. I have been to tens but not hundred of Proms, and I know that the main reverberation of the RAH is from the ceiling. Thus, in mono, I get huge sense of height from the live relays. It is experience with real concerts transposed to listening to mono reproduction in, at the time, world class quality.

The Royal Festival Hall is different, but I still sense the space, depth and whole ambience.

I have no explanation of the sense of height and width from mono radio, but it does exist for me.

But the laugh is that it probably does not exist for the initiate.

I would call replay and radio, more or less just a cue machine for me. It sets the cues and I imagine being there.

Best wishes from George

 

[tuga]

I have been following this thread and reading every post.

I have zero interest in left/right separation, My system [such as it is] is a 1957 Leak Trough-Line VHF/ FM tuner, Quad II Forty amp and ESL. It coudly be more hardly be more direct with discrete components. No pre-amp as the tuner has a nice cathode follower [variable output] that perfectly matches any mono-block valve amp.

So I am not worried by the stereo recreations of say my hero, Ella Fitzgerald, and mono records still compete, though the record side of my set does not fed the ESL. The best live VHF/FM is simply still better than almost any recording as produced and issued commercials.

So I am going to join the debate regarding vertical perception from systems designed for left/right separation or mono that does not.

If one knows a concert venue, then one knows where the reverberation comes from. I listen to The BBC Proms most nights. I have been to tens but not hundred of Proms, and I know that the main reverberation of the RAH is from the ceiling. Thus, in mono, I get huge sense of height from the live relays. It is experience with real concerts transposed to listening to mono reproduction in, at the time, world class quality.

The Royal Festival Hall is different, but I still sense the space, depth and whole ambience.

I have no explanation of the sense of height and width from mono radio, but it does exist for me.

But the laugh is that it probably does not exist for the initiate.

I would call replay and radio, more or less just a cue machine for me. It sets the cues and I imagine being there.

Best wishes from George

Do you listen in mono over one or a pair of speakers?

The simple fact that we are able to imagine a symphony hall is enough for us to expect a large space with a high ceiling.
The amount of ambience captured by the mics can/will also provide cues in that regard.

I have been only once to the RAH, when my eldest sang there in a massive children choir.
Awful acoustics, I would probably not pay for a Proms ticket, much better to listen at home.

 

[George J]

Do you listen in mono over one or a pair of speakers?

The simple fact that we are able to imagine a symphony hall is enough for us to expect a large space with a high ceiling.
The amount of ambience captured by the mics can/will also provide cues in that regard.

I have been only once to the RAH, when my eldest sang there in a massive children choir.
Awful acoustics, I would probably not pay for a Proms ticket, much better to listen at home.

Two points.

First, just one ESL [which may well be the best mono speaker ever made, especially in its 1957 mono voicing].

I cannot imagine myself ever wanting to actually go to the RAH again. The radio relays are much more musically lucid, as Elgar observed as early as 1927!

He wrote to Fred Gaisberg [HMV record producer], and GB Shaw about a concert where he told them to "listen at home," to his concert playing his Second Symphony.

Three weeks later HMV made a very successful recording [produced by Gaisberg] of Elgar's Second Symphony at Kingsway Hall [now demolished] which was a great concert venue, and wonderful studio used by both EMI and Decca for fifty years.

The hall had a unique quality for opera and oratorio in that the choir were in a balcony above the orchestra that was equi-distant from the main microphone, giving a perfect natural balance, and yet in those esteemed recordings one never senses that choir is "above" the orchestra!

It is a queer old business!

Best wishes from George

 

[Tony L]

First, just one ESL [which may well be the best mono speaker ever made, especially in its 1957 mono voicing].

Do you find much difference/have a preference between vintage ‘true mono’ recording where everything was mic’d mixed with mono being the target product in mind, and modern recording where what you are hearing is effectively a ‘fold-down’ of a stereo (or even multi-channel/surround) recording? I’m curious as in the jazz vinyl world ‘fold-downs’, i.e. where a stereo copy was the main product and the mono mix was just a summing of both channels rather than a dedicated mono mix are somewhat frowned upon.

 

[camverton]

I have been following this thread and reading every post.

I have zero interest in left/right separation, My system [such as it is] is a 1957 Leak Trough-Line VHF/ FM tuner, Quad II Forty amp and ESL. It couldy be hardly be more direct with discrete components. No pre-amp as the tuner has a nice cathode follower [variable output] that perfectly matches any mono-block valve amp.

So I am not worried by the stereo recreations of say my hero, Ella Fitzgerald, and mono records still compete, though the record side of my set does not fed the ESL. The best live VHF/FM is simply still better than almost any recording as produced and issued commercials.

So I am going to join the debate regarding vertical perception from systems designed for left/right separation or mono that does not.

If one knows a concert venue, then one knows where the reverberation comes from. I listen to The BBC Proms most nights. I have been to tens but not hundred of Proms, and I know that the main reverberation of the RAH is from the ceiling. Thus, in mono, I get huge sense of height from the live relays. It is experience with real concerts transposed to listening to mono reproduction in, at the time, world class quality.

The Royal Festival Hall is different, but I still sense the space, depth and whole ambience.

I have no explanation of the sense of height and width from mono radio, but it does exist for me.

But the laugh is that it probably does not exist for the initiate.

I would call replay and radio, more or less just a cue machine for me. It sets the cues and I imagine being there.

Best wishes from George

I love that expression “I would call replay and radio, more or less just a cue machine for me. It sets the cues and I imagine being there.” and the better it does that, for us as individuals, the better hifi it is.

 

[George J]

Dear Tony, That is an interesting point.

The best pure mono recordings defy their age - pre 1955 or '54 for classical. But they do reflect the age in terms of tape technology.

The real significance for me also concerns recording made as stereo, but until the early 1970s these tended to be completely mono compatible. This involves the crucial element of phase coherence between the two stereo channels. If coherent, then a pure mono signal can be obtained. With later stereo and multiple microphone set-up the mono can be muddled by phase effect comb-filtering.

As it goes, I have little interest in performing artists of the older era after Otto Klemperer, at least till the return to simpler two coherent microphone techniques as for Trevor Pinnock so that very complicated era in the mid-1970s to the current day for very big productions, was mostly avoided in smaller baroque recordings. I am not really interested in Herbert von Karajan's forty-eight channel digital confections.

So I am blessed by the BBC live relays that are mono compatible, and the bloom of new recordings of smaller scaled recording that are so rewarding.

Hope that gives a clear idea. Best wishes from George

EDIT PS: May I send the reader to my small thread in the Music Room [Classical] where I post three YouTube posts of mono recordings [chosen because they are supreme musically rather than technical considerations] ... Beethoven, Leonore Overture Number One.

One from the 1930s, so a wax cut HMV from the Queens Hall in Langham Place, Portland Street next to BBC Broadcasting House, and another from an RCA-NBC [New York] acetate recording in the Wartime, and finally and best of all, Klemperer in pure mono in 1955 in the Kingsway Hall for EMI on tape. The direct cut recordings are rather good [not without consideration of being seriously old], but in 1955 EMI really had mastered the art of recording phenomenal quality mono tape. And Klemperer is at his mighty best in Beethoven.

As this is the hifi section, it may be observed from that 1955 [single take] session, the balance is absolutely clear, the sense of space is impeccable, and the tone is astonishing for recording done sixty-six years ago. And yes, there is even a sense of the orchestra being "down there" on the stage, somewhat below the ear of the listener. How did they manage that with just one tape track balanced directly? Sometimes a relatively simple set-up manages to be be better without artificial manipulations of the most sophisticated modern arrangements.

 

[davidsrsb]

The reflections are delayed in time, so it's a bit more complicated. Answering how this will be perceived overall isn't simple, and could be affected by other context (e.g. off-axis FR). But yeah, I expect the perception will be different in room compared to anechoic.

This phantom centre dip is a frequency domain issue.
When you look at time domain, a real centre source gives a single arrival at both ears at the same time.
A stereo speaker simulation of a centre source gives a first arrival at both ears at the same time and a second crossed over about 250us later. Several ms later still all the real room reflections start arriving

 

[davidsrsb]

Do you find much difference/have a preference between vintage ‘true mono’ recording where everything was mic’d mixed with mono being the target product in mind, and modern recording where what you are hearing is effectively a ‘fold-down’ of a stereo (or even multi-channel/surround) recording? I’m curious as in the jazz vinyl world ‘fold-downs’, i.e. where a stereo copy was the main product and the mono mix was just a summing of both channels rather than a dedicated mono mix are somewhat frowned upon.

Is the original ESL different to the ones used for stereo? I am interested that a single ESL and a corner horn have a lot in common in low dispersion. The frequency balance change between a true mono chain and stereo pretending to be mono are the greatest for these types of speakers.

 

[Tony L]

Is the original ESL different to the ones used for stereo?

No, exactly the same thing, people just tended to buy another one when they wanted stereo, hence many old ‘pairs’ having serial numbers a long way apart. Same with Quad II power amps, you just bought another and the stereo 22 preamp, so a very nice upgradable system from Quad that adapted seamlessly to new developments.

PS Tannoys much the same and you occasionally see bizarrely mismatched vintage setups that were obviously upgraded to stereo with say a Silver on one side and a Red on the other!

 

[darrenyeats]

This phantom centre dip is a frequency domain issue.
When you look at time domain, a real centre source gives a single arrival at both ears at the same time.
A stereo speaker simulation of a centre source gives a first arrival at both ears at the same time and a second crossed over about 250us later. Several ms later still all the real room reflections start arriving

I think you misunderstood my post, which quoted

The effect of room reflections will be to reduce the extreme peaks and troughs from the simple two paths to two ears model.

This mechanism sounds like it could be important for steady state signal but effects are harder to reason about for music. Reflections delayed beyond a certain time aren't perceived as a modifier to the direct sound but processed another way. I wasn't disagreeing, just adding.

 

[windhoek]

This is a topic that fascinates me and I think was part of my ongoing shift away from conventional big multi-driver speakers. There is no doubt some albums on some systems give a unmissable sense of height. As an example try the ‘Someday My Prince Will Come’ album by Miles Davis. It is a brilliant album and I’d not audition any component or change without playing it. On some systems Miles’s close mic’d and astonishingly present trumpet comes from way above the speaker plane, really high up in the air. Try it. It is a really odd effect that I’ve heard on many, many entirely systems in many different rooms (I’ve had this album for 30 years or more). It is an album I’ll often play on other people’s systems, at dems etc, so a far wider scope than my own kit/taste in audio.

I have first hand recording studio experience etc; I understand how mics work, I understand a fair bit about mic positioning, outboard FX (which would be very thin on the ground when this album was recorded in the early 60s) etc, so I agree fully with the ‘there is no height information in stereo’. I accept that as fact, yet the phenomenon clearly exists, so what is it we are hearing? My guess is a combination of phase error and the for some reason widely tolerated ‘tweeter at the top, mid band in the middle, bass unit(s) lower down the cab, port at the bottom’ type speaker design. A design I now consider flawed, and the more drivers the more flawed it becomes. Phase error on recordings is a very confusing topic and certainly exists on pretty much any multi-mic recording, so this may be a combination of imperfect recording phase and multi-driver speaker playback. I don’t know, but certainly some recordings can generate an impression of real height in some scenarios, so I’m curious as to explanations/theories.

Folk should give Someday My Prince Will Come a go, it is a truly great album so nothing to lose, and I’ll be interested if anyone hears the height thing I describe.

PS One thing that I hate with a passion is piano mic’d in the way described upthread with regard to the Kate Bush album. I can’t bring that particular track to mind, but even the wonderful ECM are guilty of this ‘giant stereo piano the size of a stage’ thing at times, and on some big multi-driver speakers the thing invariably slopes (right hand high, left low) and sounds like the stage isn’t level. One often fears the piano will roll off.

The Kate Bush piano soundstage thing on Feel It would only seem over the top if your speakers and you were positioned in a large far-field setup. If your speakers were between 1-2m apart and you sat roughly the same distance away, the piano imaging would sound pretty good and fairly appropriate to the real thing.

Nevertheless, Someday My Prince Will Come sounds great no matter what so full agreement there

 

[Steve 57]

I have had over the years a few mono setups , all short term. It was noted in the 50s that the introduction of stereo caused a drop in resultion, which is quite understandable if you understand the effect high cross talk has on the overall sound.
Then in the early sixties the many stereo amps which could run the pre and tuner off the amplifiers power supply really messed with the resultion on all but the simplest of music.
For me, once I found out why most stereo equipment spoiled the original recording to some extent, It give me the knowledge to build kit that didnt spoil, or rather didn't react to the original recording and play its own version of it.
I would say from my experence, good stereo is equal to good mono when it comes to resultion, although, surprisingly it still today appears much harder to achieve in stereo!

 

[Tony L]

If your speakers were between 1-2m apart and you sat roughly the same distance away, the piano imaging would sound pretty good and fairly appropriate to the real thing.

The piano thing, like rock drum panning, is just a pet hate of mine. A piano is typically plonked on stage with the keyboard at the left and the top open to reflect the sound in the direction of the audience. There is no ‘right/left’ to it’s sound unless you are actually playing the thing, and even then it is pretty subtle. From the audience perspective it is basically a big solid 9 foot sound source. The treble side is slightly closer to you (the listener) than the bass, but that will have no impact whatsoever on what you hear as the soundboard resonates/amplifies as a whole and a lot of sound is reflected from the lid. The right hand out of one speaker, left out the other is entirely a studio creation (like rock drum panning). It simply does not exist in the real world.

PS It also really annoys me that most digital pianos, DAW plug-ins etc do the panning thing by default. It has become the accepted norm even though it is so obviously wrong.

 

[windhoek]

The piano thing, like rock drum panning, is just a pet hate of mine. A piano is typically plonked on stage with the keyboard at the left and the top open to reflect the sound in the direction of the audience. There is no ‘right/left’ to it’s sound unless you are actually playing the thing, and even then it is pretty subtle. From the audience perspective it is basically a big solid 9 foot sound source. The treble side is slightly closer to you (the listener) than the bass, but that will have no impact whatsoever on what you hear as the soundboard resonates/amplifies as a whole and a lot of sound is reflected from the lid. The right hand out of one speaker, left out the other is entirely a studio creation (like rock drum panning). It simply does not exist in the real world.

PS It also really annoys me that most digital pianos, DAW plug-ins etc do the panning thing by default. It has become the accepted norm even though it is so obviously wrong.

Interestingly, I can't recall ever noticing a full pan piano sound like that before. Not just on Feel It, but on any track. I do agree it's a made-up thing, but that has no bearing on whether one enjoys the end result, or not as the case may be. As for drums, I was listening to Ege Bamyasi the other night and Jaki's fills sounded great. Sometimes they're roll across the soundstage and sometimes they're located in one position, but in all cases they just sound great.

 

[Tony L]

As for drums, I was listening to Ege Bamyasi the other night and Jaki's fills sounded great. Sometimes they're roll across the soundstage and sometimes they're located in one position, but in all cases they just sound great.

Can’s drum sound of that era was superb IMO, they were very limited by the technology they had to hand/could afford, so a lot of it is live to Revox two-track with some tape editing/splicing etc later. They were not using a lot of mics on the kit, hence it sounding far more cohesive and like a jazz kit rather than the usual over-processed rock aesthetic. I’m sure Jaki brought a lot of skills in this regard as he was already an accomplished jazz drummer before Can so had been recorded many times.

 

[a.palfreyman]

Well, I listened two 2 of my favourite jazz albums Saturday afternoon: Cannonball Adderley, Somethin' Else and Sonny Rollins, The Bridge.
The piano work on Somethin' Else seems to me to sit forward of the other instruments, mostly just left of centre (but occasionally moves to centre or just to the right) but generally sits below the plane of other instruments and the sax and trumpet seem to merge hard left. The guitar work on The Bridge is hard left and seems to sit below the other instruments. Now my home-brew speakers use 8" bass units at the bottom and 4" mids just above the tweeters (1" metal domes) which sit at ear level. Bass to mid cross-overs are 1st order electrical so there is a big spread of overlap between the two. The 90 degree phase difference between the two drivers means that the maximum output in the bass/mis cross over region is 15 degrees downwards. I wonder if this dispersion pattern (i.e. towards the floor) is what makes the instruments which sit squarely in this region seem 'lower' than other instruments due to an enhanced floor reflection?

 

[Tony L]

The piano work on Somethin' Else seems to me to sit forward of the other instruments, mostly just left of centre (but occasionally moves to centre or just to the right)…

This is fairly common on Rudy Van Gelder recordings and is a result of bleed between instruments due to the live recording, e.g. when he fades up a mic feed for a sax solo it also picks up some piano or drums and they move slightly in the soundstage as a result. There is a very obvious example somewhere on Coltrane’s Blue Train where the whole drum kit moves for a solo on one of the brass instruments!

 

[a.palfreyman]

^^^
I'll give that a listen at the weekend as it's a while since I've heard it.

 

[chartz]

Funny that — I was listening to Blue Train yesterday!
Good, realistic imaging until the last third of the piece where everything becomes messy.
Two takes assembled?
I was talking to a renowned sound engineer only yesterday, we talked a lot about sound quality, how instruments are captured to sound realistic on good speakers (like my Cabasses).
But he never mentioned imaging… and yet his recordings are incredibly realistic, displaying true 3D stereophonic imaging!

 

[tuga]

Well, I listened two 2 of my favourite jazz albums Saturday afternoon: Cannonball Adderley, Somethin' Else and Sonny Rollins, The Bridge.
The piano work on Somethin' Else seems to me to sit forward of the other instruments, mostly just left of centre (but occasionally moves to centre or just to the right) but generally sits below the plane of other instruments and the sax and trumpet seem to merge hard left. The guitar work on The Bridge is hard left and seems to sit below the other instruments. Now my home-brew speakers use 8" bass units at the bottom and 4" mids just above the tweeters (1" metal domes) which sit at ear level. Bass to mid cross-overs are 1st order electrical so there is a big spread of overlap between the two. The 90 degree phase difference between the two drivers means that the maximum output in the bass/mis cross over region is 15 degrees downwards. I wonder if this dispersion pattern (i.e. towards the floor) is what makes the instruments which sit squarely in this region seem 'lower' than other instruments due to an enhanced floor reflection?

Can you turn off the tweeter and listen to the guitar? Also try listening with the midrange off and the other drivers on. It may be a very elucidating experience.
What are the crossover frequencies?